Melatonin Can Lower Your Risk Of Prostate Cancer.
Research does not support the claim that melatonin helps lower the risk of prostate cancer.
Melatonin is a hormone secreted by the pineal gland in a circadian rhythm. Melatonin exhibits some anticancer properties in animal models. Night shift work which disturbs circadian rhythm and suppresses melatonin secretion was classified as a potential carcinogen by the International Agency for Research on Cancer.
Websites including Science Daily have made claims that melatonin may lower prostate cancer risk.
The original study behind this claim was a collaborative research project between researchers in Harvard, the National Institutes of Health, Iceland and Sweden. This research consortium has a special interest in melatonin and prostate cancer and has numerous other related publications.
In this particular study, they did a case-control study of some of the men who were enrolled in a larger study known as Age Gene Environmental Susceptibility [AGES], Reykjavik Cohort.
92 Icelandic men who were enrolled in AGES and who did not have prostate cancer participated in a nested case-controlled substudy. Study subjects collected a single early morning urine sample which was then analyzed for 6-sulfatoxymelatonin levels. Information on sleep disturbance for these men was already available as part of the AGES database.
The study showed that men who reported sleep problems had lower levels of urinary 6- sulfatoxymelatonin. A total of 111 study participants were diagnosed with prostate cancer. Of these, 24 were diagnosed with advanced prostate cancer. Men with lower urinary 6-sulfatoxymelatonin levels had a statistically significant higher risk of advanced prostate cancer.
This study has a number of significant limitations. Firstly, key clinical information such as prostate specific antigen and histology results were not available in 35% of study participants. Secondly, the results are based on a single urinary melatonin measurement. Thirdly, key relevant confounders such as vitamin D were not available for the study cohort. Fourthly, the study population was limited to elderly Icelandic men who may not as such be representative of the general population.
In summary, there is no scientific proof that melatonin (and specifically melatonin supplementation) can lower your risk of prostate cancer.